Sewing machine

ABSTRACT

Sewing machine, here illustrated as a machine for simultaneously embroidering a plurality of pieces of goods with an identical pattern or for embroidering a plurality of identical patterns on a single piece of goods. The illustrative machine comprises a plurality of embroidering stations, a plurality of embroidering mechanisms each of which is disposed at a rsspective embroidering station, and means for traversing the goods relative to the mechanisms at the stations to embroider the goods in accordance with the pattern.

United States Patent [72] Inventors Albert A. Schmedding;

Ernest L. Heller, both of Oradell, NJ. [21] Appl. No. 720.632 [22] Filed Apr. 11, 1968 [45] Patented July 27,1971

[73] Assignee Bergeufleld Development Co., Inc.

Dumont, NJ.

[54] SEWING MACHINE 18 Claims, 15 Drawing Figs.

[52) US. Cl. 112/221, 112/98, ll2/155, 112/239, 112/219 [51] Int. Cl...., D05b 69/02 [50] Field of Search 112/221, 182, 258

[56] Relerences Cited UNITED STATES PATENTS 554,392 2/1896 Moore 112/182 8/1919 Lutz .1 112/221 (X) 2,709,978 6/1955 Adler 112/258 (X) 2,889,792 6/1959 Scheibel 112/221 (X) 3,465,698 9/1969 Hacklander 112/221 X Primary E.mminerRichard J. Scanlan, Jr. Aitorneys Dale A. Bauer, John L. Seymour and Bauer and Seymour ABSTRACT: Sewing machine, here illustrated as a machine for simultaneously embroidering a plurality of pieces of goods with an identical pattern or for embroidering a plurality of identical patterns on a single piece of goods. The illustrative machine comprises a plurality of embroidering stations, 21 plurality of embroidering mechanisms each of which is disposed at a rsspective embroidering station, and means for traversing the goods relative to the mechanisms at the stations to embroider the goods in accordance with the pattern.

PATENTEU JUL27 Ian 3.595; 188

SHEET 1 [1F 6 INVENTORS 5 1- ALBERT A. SCHMEDDING N BY ERNEST L. PFEIFER ATTORNEYS PATENTED JUL2'! l9?! SHEET 2 OF 6 IN VENTORS ALBERT A. SCHMEDUING L. PFEIFER ATTO EYS ERNEST PATENTEDJULZ'IIQYI 3595.188

SHEET 3 OF 6 INVENTORS v ALBERT A. SCHMEDDINC BY ERNEST L PFEIFER.

ATT NEYS PATENTEDJULZVIQ?! v 3,5951% SHEET 5 BF 6 184. INVENTORS ALBERT A. SCHMEDDING BY ERNEST L. PFEIFER M 5 [at AT HNEYS SEWING MACHINE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a sewing machine, in the embodiment shown'such machine having a plurality of sewing stations. The illustrative machine is adapted to hold pieces of goods which are to be embroidered simultaneously in the same pattern. At each station there is positioned an embroidering mechanism in the form of a sewing head and associated looper, the goods being traversed relative to the mechanisms by a pantograph device which follows a pattern or template.

2. Description of the Prior Art Prior art multiple head embroidery machines have employed a plurality of aligned heads carrying needle bars, the heads being disposed above respective embroidering stations provided with means for positioning goods to be embroidered. A pattern following device, such as a jacquard control mechanism, is provided for moving the goods at the embroiderin g stations relative to the heads of the machine.

In such prior machines, the needle bars of the heads have been driven by branch shafts coupled to a common drive shaft which itself is driven from one end and each looper is coupled to its respective needle bar branch shaft by mechanism housed in a hollow vertical throat or pedestal of the head casting or housing and by its individual variable speed coupling. The load upon the common drive shaft, particularly under normal conditions which require rapid starting and stopping of the machine, tends to twist the common drive shaft substantially, so that various ones of the heads may run appreciably out of phase with respect to the other heads. Additionally, the throats or pedestals severely limited the field size or embroidery pattern and interfered with the connection between the pantograph and the hoops or other supports for the goods.

Further, although a clutch has been provided in each of the drive trains from the said common drive shaft to the needle bars, whereby any one of the heads may be disconnected, such clutches have had an operating wheel which is mounted upon and rotates with the needle bar branch shaft within the sewing head which forms a major part of each drive train. Such clutch operating wheels are difficult to grasp and operate when a head is running.

Prior multiple head sewing machines such as embroidery machines have incorporated thread tension responsive means to stop the entire machine upon the breaking or depletion ofa thread being appliedby any one sewing mechanism of the machine. Such means, however, has been complicated and prone to failure. No satisfactory means has been provided for indicating which head of the machine has the broken or depleted thread. Searching for the broken thread is unduly time-consuming, since the break in a thread may not be readily apparent.

Prior machines have employed retractable presser or stripper feet which in their lower terminal position lightly engage or are disposed close to the upper surface of the goods being sewed. The present machine incorporates novel means for altering such lower terminal position of the feet, whereby to accommodate the machine to the handling of goods of different thicknesses.

SUMMARY OF THE INVENTION The multiple head sewing machine of the invention includes improved means to drive the needle bars and loopers of all of the sewing mechanisms simultaneously from a common drive means, improved individual clutch means for each mechanism to permit the stopping of any desired one of the mechanisms while the machine is in operation, improved thread tension responsive means to stop the entire machine at an advantageous point in its operating cycle upon the breaking or depletion of a thread being applied by any one sewing mechanism of the machine, novel signalling means to indicate the particular sewing mechanism the thread of which is broken or depleted, and means for raising the stripper foot associated with each head from contact with the goods before the goods is shifted relative to the needle to form the design being embroidered. The improved means contemplated by the invention for mounting and driving the sewing heads and loopers permits more advantageous mounting of the holders for the goods, the application of larger patterns to larger fields and the embroidering of yard goods and continuous ribbons.

BRIEF DESCRIPTION OF THE DRAWING The above and further objects and novel features of the invention will more fully appear from the following description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only, and are not intended as a definition of the limits of the invention.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

FIG. 1 is a somewhat simplified view in perspective of an illustrative multiple head embroidery machine in accordance with the invention, only three of the heads of the machine being shown, the cams and breaker points or contacts operated thereby'associated with one of the means for driving the opposite ends of the upper and lower drive shafts being omitted for clarity of illustration, and the means for holding and moving the goods to be embroidered being omitted;

FIG. 2 is a view in end elevation of the upper portion of the machine, the view being taken in the direction from left to right in FIG. I; 1

FIG. 3 is a view in vertical axial section through an end of the looper driving shaft, the section being taken along the line 3--3 of FIG. 2, certain of the parts being shown in elevation;

FIG. 4 is a view in perspective of one of the two variable speed couplings employed to drive the looper drive shaft, portions of the walls of the coupling housing being broken away;

FIG. 5 is a view in perspective of a sewing head of the machine and the part of the table associated therewith, the front cover plate of the head being removed, the needle being shown in raised position near the start of its downward stroke, the view being taken from line 5-5 of FIG. 7, the embroidery station providing means being omitted;

FIG. 6 is a view similar to FIG. 5 but with the needle bar shown later in its downward stroke and with the point of the needle about to enter the goods (not shown) being embroidered;

FIG. 7 is a view in vertical section through a sewing head and an associated looper of the illustrative machine, the section being taken generally along the line 7-7 of FIG. 5, certain of the parts being shown in elevation, the means providing an embroidery station cooperating with such head and looper being shown in phantom lines;

FIG. 8 is a fragmentary view in vertical section through a sewing head, the section being transverse to the length of the head and taken along line 8-8 of FIG. 7;

FIG. 9 is a fragmentary view in vertical section through a thread break detector employed at each head of the illustrative machine, the detector incorporating a switch which is here shown in closed position;

FIG. 10 is a view similar to FIG. 9, but with the switch in open position;

FIG. 11 is a fragmentary view in front elevation of the thread break detector, the view being taken in the direction from right to left in FIG. 9;

FIG. 12 is somewhat schematic view in front elevation of a sewing head in accordance with the invention, the needle being shown as just having started its downward stroke, the thread tension lever being in substantially its uppermost position, and the thread extending between the thread tensioning means on the head and the eye of the needle being under appreciable tension;

FIG. 13 is a view similar to FIG. 12 showing parts of the sewing head in the position which they assume in a later portion of the sewing cycle, the point of the needle being shown as having descended so as to pass downwardly through the goods (not shown) being embroidered, the thread tension lever being in the upper portion of its downward stroke, and the thread extending between the thread tension means on the sewing head and the eye of the needle being in slack conditron;

FIG. 14 is a fragmentary view in horizontal section through the clutch of a sewing machine head, the section being taken along the line 14-14 of FIG. 7, certain of the parts being shown in plan; and

FIG. 15 is a diagram of the motor control and thread break detector and signalling circuit which is employed in the disclosed machine of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings, there is shown in FIG. 1 a multiple head sewing machine adapted for use with means, which is not shown in FIG. 1 but is schematically shown in FIG. 7, which provides a plurality of embroidery stations one of which is associated with each sewing machine, that is, a sewing head and its associated looper. In such embroidery machine the embroidery station providing means, which is shown at 13 in phantom lines in FIG. 7, is adapted to support goods to be embroidered. Such means 13 has a plurality of embroidery stations thereon, of which one is schematically shown at 18. The means 13 and thus all of the embroidering stations 18, are moved in unison by a pattern following device which is conventional in the art and is not here shown.

A plurality of similar sewing machine heads are mounted upon a horizontal upper rail 11 which is supported above a main horizontal table 96 by two similar spaced, parallel end supports 12 and 14. Such manner of supporting the sewing heads provides a clear path therebeneath in a direction from the front to the rear of the machine, so that the goods being sewn or embroidered need not be limited in length. The drive for the sewing heads 10 is provided by an upper main horizontal drive shaft 16 which, as shown, is disposed rearwardly of the rail 11 and passes through a rear lower portion of each of the sewing heads. The vertically reciprocable needle bar 81 of each head is driven by means drivingly connected to shaft 16, such means including a shaft 50 within the housing of each head which is shown more particularly in FIGS. 7 and 14 and will be described hereafter.

The sewing machines shown are of the two-thread, lock stitch type, wherein the sewing heads 10 apply a first, upper or needle thread to the goods, and a looper 107 (FIG. 7) applies a second, lower or under thread thereto. The lock between threads is formed by passing the upper thread around the lower thread and tightening the two threads together in the goods being sewed.

A lower horizontal longitudinally extending shaft 17, which drives the loopers associated with each of the sewing heads of the machine, is disposed beneath the table of the machine. Shaft 17 is driven at its opposite ends through variable speed couplings 115, the couplings having at their input ends stub shafts 116 which are driven in synchronism with the shaft 16 by Timing belt and sprocket means which are shown more particularly at the left of FIG. 1 and in FIG. 2. Thus at the rear of the machine there is provided a horizontal longitudinally extending lower shaft which is driven by a motor (not there shown) through the medium of a V-belt 20 entrained over a pulley 19. At each end of the machine, outwardly of the supporting members 12 and 14, through which the ends of shafts 15, 16, and 116 extend, there is provided identical Timing belt and sprocket driving means which synchronizes the rotation of the shafts 16 and 116 and maintains them accurately in phase. Thus outwardly of support 12 there is a Timing belt 21 which is entrained over sprockets 24, 25, and 26 which are affixed to shafts 15, 16, and 116, respectively. Outwardly of support 14 there is a Timing belt 21 which is entrained over pulleys 24', 25', and 26 (FIG. 1) which are affixed to shafts 15, 16, and 116, respectively. Belts 21 may be tensioned by adjustable idle pulleys 27, as shown. By reason of such driving of the shafts 16, 116, and 17 by shaft 15, the twisting of such shafts under rapid starting and stopping conditions is minimized, whereby the needle bars and loopers of the various sewing machines are maintained accurately in phase.

The frame or housing 29 of each sewing head 10 is of generally U-shape in side elevation, as shown in FIGS. 1 and 7. Housing 29, which is hollow and generally downwardly open, has a depending rear skirt 30, a first rear intermediate rib 31, a second intermediate rib 32, spaced forwardly of rib 31, and a vertical hollow front portion 34 within which the vertically reciprocable needle bar 81 and its driving means are mounted. The upper portion of the rear wall or skirt 30 is thickened at 35 to provide support for a bearing 51, received in a bore in housing portion 35, which supports the rear end of the shaft 50 of the sewing head. A portion 36 of wall 30 is of somewhat thinner section. As shown in FIG. 8, the horizontal driving shaft 16 is journaled in a bearing 39 mounted in the housing 29 of the sewing head 10. Such bearing, which is of the type known as a ball bearing, has an outer race 40 which is fixedly held within a bore 37 in a thickened portion 35 ofthe housing 29 between an inner and an outer spring ring 41 and 42, respectively, disposed in annular grooves in bore 37. The inner race of the bearing is positioned on shaft 16 by a spacer sleeve 46 and a collar 44 which is secured to the shaft as by a pin or Allen screw 45.

Affixed to the shaft 16 within the housing 29 there is a helical gear 46 having a collar 47, the collar being secured to shaft 16 as by a set screw 49 in abutment with spacer 46'. It will be apparent that with such construction any one of the sewing heads 10 may be removed from the machine upon the loosening of the shaft 16 from each of its bearings 39 and helical gears 46, as well as the removal of the end driving sprockets from the shaft, so that the shaft may be readily withdrawn axially from all of the heads. Following this the desired heads 10 are removed from the rail 11, and the shaft 16 with its bearings and helical gears are reassembled within the remaining sewing heads 10, and the shaft 16 is then remounted in supports 12 and 14.

The needle bar driving shaft 50 of each sewing head is rotatably supported at its rear in the above mentioned ball bearing 51 and adjacent its forward end in a sleeve bearing 52 which is mounted in a bore in the rib 32 of the housing 29. Meshing with the helical gear 46 on shaft 16 is a second helical gear 54, gear 54 being affixed to a sleeve 55 which is mounted on shaft 50 for rotation with respect thereto. The sleeve 55 and the gear 54 thereon are retained from travel axially with respect to the shaft 50 by spring rings received within annular grooves in the shaft 50 at each end of the sleeve 55. Gear 54 and sleeve 55 are selectively drivingly connected to shaft 50 by a clutch 53, which is constructed as follows.

Within an eccentric blind bore in the forward face of the sleeve 55 there is mounted a forwardly extending pin 56. A reciprocable sleeve 57 mounted upon shaft 50 forwardly of sleeve 55 is keyed to the shaft for rotation therewith through the medium of a key 60 affixed to the shaft and received within an axially extending groove 59 in the inner surface of the sleeve 57. At one location angularly thereabout the sleeve 59 is provided with a rearwardly open recess 61 which selectively accurately receives the forward end of the eccentric pin 56. It will be seen that the gear 54 may be drivingly connected to the shaft 50 through the medium of the clutch sleeve 57 in only one angular position of such parts relative to each other. Thus the required phase relationship between the needle bar 81 and the looper 107 of the individual sewing machine is restored when the sleeve 57 is returned to its rearward, engaged or driving position, shown in FIG. 7, after having been operated to disconnect the needle bar driving shaft 50 from the shaft 16.

The sleeve 57 is constantly urged into its rearward, clutchengaged position, by a coil compression spring 62 which is telescoped about shaft forwardly of the sleeve 57, and which acts between the forward end of sleeve 57 and an abutment ring 63 affixed to shaft 50, as shown. The clutch sleeve 57 may be shifted axially of the shaft 50 selectively to disengage and engage the clutch by the following means. An annular groove 64 is provided in the outer surface of clutch sleeve 57, such groove receiving an eccentric projection or pin 67 (FIG. 14) on the inner end ofa clutch operating cross shaft 65 which is journaled in the housing 29 on one side thereof and extends outwardly therethrough. A lever 66 affixed to the outer end of shaft 65 may be thrown in one direction to retract the clutch sleeve 57 forwardly against the pressure of spring 62 to disengage the clutch; when such lever 66 is thrown in the other direction, the spring 62 thrusts sleeve 57 rearwardly so that pin 56 on sleeve 55 may be received within recess 61 in sleeve 57. For a purpose to more fully appear hereafter, the engagement of pin 67 with the radial wall of groove 64 during clutch disengagement tends to prevent rotation of sleeve 57 and shaft 50.

Mounted upon the rear end of the shaft 50 is a hand wheel 69 by which the needle bar 81 of the head 10 may be manually driven, as for reengaging the clutch, positioning the needle 91, or as required for servicing or adjustment of the sewing head mechanism. Affixed to the forward end of shaft 50 coaxially thereof and within the portion 34 of the head there is a circular cylindrical element 70 which functions both as a barrel cam for driving a thread tensioning lever 76 of the sewing head and as a crank for reciprocating the needle bar 81 of the head vertically. Element 70 has a curved parallel sided cam groove 71 in its peripheral surface, such groove receiving a cam follower roller on the outer end of an arm 73 ofa bell crank 72 which is mounted for oscillation about a horizontal pivotal support 74 affixed to the frame 29 of the head. The thread tensioning lever 76, which forms the second arm of the bell crank, extends outwardly through a vertical slot 77 in a plate 79 which covers the forward end of the housing 29 of the head. Lever 76 has at its outer end a guiding eye 80 through which the upper thread 145, which is applied by the sewing head 10, passes in its travel to the needle, as shown in FIGS. 12 and 13.

The needle bar 81, which is in the form ofa circular rod, is guided at its upper end within a vertical sleeve 82, the upper end of the sleeve being affixed to the upper wall of portion 34 of the housing 29 of the head, as shown in FIG. 7. The lower portion of the needle bar 81 is guidingly received within a short vertical sleeve 84 coaxial of sleeve 82, sleeve 84 being affixed to a lower forward part 85 of the portion 34 of the housing. Driving connection between the element 70 on shaft 50 and the needle bar 81 is effected by an eccentrically mounted crank pin 86 on the forward end of the element 70, a connecting rod 87 pivotally secured at its upper end to the pin 86 and at its lower end to a pivot pin 89 which projects rearwardly from a boss 90 connected to the needle bar. The lower end of the needle bar is provided with a vertical blind bore receiving the upper, shank end of the needle 91, the needle being retained in such bore by a needle retaining screw 92.

As shown in FIG. 7, the machine has longitudinally extending lower frame members 94 and 95 which extend from end to end thereof and which, with other frame members, not shown, support the table 96. Frame members 94 and 95 are connected at their ends by the lower ends of supports 12 and 14, the lower end of the latter, in which one end of the drive shaft 15 is journaled, being shown in FIG. 7. At an opening 97 through the table 96 in alignment with each of the sewing heads 10 and the embroidery stations 18 on the member 13 there is provided a looper unit 99, the upper portion of the housing of which is disposed in the opening 97 through the table with the flat upper surface of housing portion 100 flush with the top of the table. As shown, the forward end of the looper unit is supported upon the frame member 95, and the rear end of the looper unit is secured to the downwardly extending flange of frame member 94. The forward end portion 101 of the looper unit frame presents a rectangular opening th'erethrough which provides access to the bobbin of the looper, such opening being covered by a removable plate 102, the upper surface of which lies flush with the top of the table 96.

A further, fixed cover portion 104, rearwardly of plate 102, is provided with a vertical needle receiving hole 105 thereth'rough. The lower or under thread is supplied by a bobbin (not shown) disposed within a bobbin holder 106 and is fed to a rotatable looper 107 which is affixed to the forward end ofa looper driving shaft 109. The looper 107, which is of conventional construction, has a hook 108 thereon which rotates with the looper 107 and shaft 109. As is well known in the art, upon the descent of the needle through the goods being sewed, the loop of the upper or needle thread 145 which is formed beneath the goods is taken by the point of the hook 108 on the looper and is passed around the bobbin, which contains the lower or under thread and a tensioning device for such lower thread. At this time, the loop in the needle thread is permitted to enlarge under substantially no tension by the descent of the needle thread takeup lever 76. After the upper thread has been passed about the lower thread, the two threads are tightened together to form a lock stitch.

The looper rotating shaft 109 is mounted for rotation in rear and forward bearings 110 and 111, respectively, in the looper frame, shaft 109 being rotated by the shaft 117 through the medium of meshing helical gears 112 and 114 which are affixed to shafts 17 and 109, respectively. The shafts 109 and the loopers 107 carried thereby of the various sewing machines are all similar and are drivingly connected so as to be rotated in synchronism and in phase. In order to rotate the looper of a round bobbin, lock stitch sewing machine at a slower speed when the upper and lower threads were being looped together than during the remainder of the rotation of the looper there was formerly provided a variable speed coupling for each looper, such coupling being interposed in the driving train therefor. In accordance with the present invention, only two variable speed couplings 115 are provided, one at each end of the looper drive shaft 17. This results in a more rugged, trouble free, and economical machine.

Since the two couplings 115 are identical, only one is particularly shown and described. Such variable speed coupling is shown in detail in FIGS. 3 and 4. As there shown, the inner end of a stub shaft 116 which is driven by the Timing belt 21 through the sprocket 26, is mounted for rotation in a sleeve bearing 117 which is mounted in a bore in the lower part of support member 12 and an aligned bore in one side 121 of a housing for the coupling. The confronting outer end of the looper drive shaft 17 is mounted in a bearing 119 in the opposite wall 122 of the housing. Affixed to the inner end of the stub shaft 116, as by being pinned thereto as shown, is a first, longer crank 124 disposed within the housing. A second, shorter crank 125, also within the housing, is affixed to the outer end of the looper drive shaft 17. A link 126 connects the crank pin 127 on crank 124 to the crank pin 129 on crank 125. Such variable speed coupling, which is conventional, is so disposed relative to the shafts 116 and 17 as to drive the looper 107 at a slower speed as the point or horn 108 thereof approaches, passes by, and leaves the path of the needle 81 than during the remainder of the rotation of the looper.

The sewing machine of the invention is provided with a presser foot which substantially engages the upper surface of the goods being sewed or embroidered from the time the needle enters the goods until the needle is withdrawn therefrom, thereby functioning to aid in retaining the goods in place and to prevent its substantial rising as the needle is withdrawn from it. Such presser foot, however, is provided with means whereby it is elevated from the goods upon the upward travel of the needle after having been withdrawn therefrom, so that the goods is free for travel in whatever direction is required of it by the pattern following mechanism before the next downward stroke of the needle. The presser foot 130 and its operating mechanism are particularly shown in FIGS. 5, 6, and 7 Stripper foot 130 is formed as an integral lower part of a slide member 131, the upper and intermediate portions of which are straight and are disposed vertically. The upper end of member 131 is provided with a horizontal collar 132 which surrounds and is slidable with respect to the needle bar 81. The lower end of the straight vertical portion of slide 131 is received within a forwardly open shallow vertical groove 134 in the lower portion 85 of the portion 34 of the frame of the sewing head, and is retained therein by the central lower edge portion of the cover plate 79. At its lower end the member 131 is bent rearwardly to form a generally C-shaped portion 135, the upper end of which is horizontal and has a hole 136 therethrough guidingly receiving the lower end of the needle bar 81. Below such C-shaped portion, member 131 is bent vertically and then forwardly to form the horizontal presser foot 130. Such foot has a vertical, needle-receiving hole therethrough, as shown.

Extending sidewardly from the collar 132 on slide member 31 is a horizontal arm 137 integral therewith. A coil tension spring 139, which constantly yieldingly urges the slider 131 in a downward direction, has its upper tang secured to the outer end of arm 137 and its lower tang secured to a spring anchoring pin 140 affixed to the lower forward portion of the housing of the sewing head inwardly of the cover plate 79. Travel of the slide member downwardly, however, is limited by its engagement with the boss 90 affixed to the needle bar 81. It will thus be apparent that the slide member 131 travels with the needle bar 81 from the uppermost position of the latter downwardly through the position shown in FIG. and toward the position thereof shown in FIG. 6 wherein the stripper foot 130 lightly engages or is preferably a short distance above the upper surface of the goods 138 being embroidered. As the stripper foot moves downwardly past the position thereof shown in FIG. 5, a laterally extending arm 141 on the slide member engages the upper end of a coil compression spring 142, the lower end of which is affixed to the upper end of a machine screw 144 threaded into the portion 85 of the frame ofthe head in alignment with the arm 141. Thus as the needle bar descends the slide member 131 travels freely downwardly therewith until the arm 141 engages the upper end of the spring 142, after which spring 142 progressively opposes the coil tension spring 139. When the force exerted by spring 142 equals that exerted by spring 139, further travel of the slide member 131 downwardly ceases. The screw 144 may be adjusted vertically to determine the terminus of downward travel of the presser foot 130 as commanded by the thickness of the goods 138, the screw being held in adjusted position by a lock nut, as shown.

When a sewing head is disconnected from the drive shaft by means of its clutch 56, 57 for any reason without stopping the entire machine, it may be necessary or desirable that the needle 91 and foot 130 be retained in raised position (FIG. 7) to permit free movement of cloth on table 96. Without means to prevent it, the needle and foot would creep to their lowermost positions due to the torsional forces applied to shaft 50 by the pull of tension spring 139 and the drag of continuously rotating gear 54, 55 on shaft 50. The clutch mechanism when in disengaged position functions as a brake to override the above mentioned torsional forces and thus prevents undesired rotation of shaft 50. The braking is effected by the frictional engagement between pin 67 and the radial wall of annular groove 64 under the compression ofspring 62.

Each sewing head 10 is provided with its individual upper thread 145 which is fed thereto from a spool or bobbin, not shown. Thread 145 passes through a pigtail guide 146 mounted on top of the frame of the head to a guide roll 147, and then to an adjustable thread tensioning device 149 which is shown as being of the conventional washer type. From the tensioning device 149 the thread 145 travels downwardly through a pigtail guide 151 on a thread break detector means 150. to be described, upwardly to the guiding eye 80 on the thread tensioning lever 76, downwardly to a fixed lower pigtail guiding eye 152 on cover plate 79, and thence to the eye ofthe needle 91.

As is conventional with sewing machines of the type shown, when the needle 91 is in its fully elevated position, the thread tensioning lever 76 is in its lowermost position. As the needle starts down, the lever 76 moves rapidly toward its fully elevated position, as shown in FIG. 12, causing the upper thread to become tight in the portion of its run between the tensioning device 149 and the eye of the needle 91. In all other relative positions of the needle and the thread tensioning lever 76 the thread 145 in such run thereof is relatively slack or untensioned. One of such other positions is shown in FIG. 13, wherein the needle is continuing its downward travel after it has penetrated the goods 138 and the lever 76 is also travelling downwardly. Breakage of the upper thread 145 thus virtually always occurs when such run of the thread is tensioned as shown in FIG. 12.

The machine of the invention incorporates means whereby the breakage of a thread both energizes a signal device associated with the particular sewing machine whose thread has broken, and also deenergizes the driving means for all of the sewing heads of the machine and quickly brings the sewing machines to a stop. The thread break detector means and the machine controlling elements and circuit associated therewith are shown in FIGS. 2, 9,10,11, and 15.

As shown in FIG. 12, the pigtail guide 151 of the thread break detector 150 is disposed laterally between and below both the tensioning means 149 and the lever 76. Guide 151 thus forms the thread 145 into a salient or V-shaped run with the guide 151 at the bottom thereof. Guide 151, which forms a part of the thread break detector, is mounted for resilient deflection upwardly by the unbroken thread 145 when the parts of the sewing machine are in the position shown in FIGS. 10 and 12. Guide 151 also forms the upper of two cooperating electrical contacts which are opened when the thread is tensioned as in FIG. 12 and which are closed during all other portions of the cycle of the sewing machine. If, however, the thread 145 should break, the contacts associated with the thread break detector remain closed throughout the entire cycle and, as a result, not only energize the above-mentioned signalling device but cause the driving means for the entire machine to be deenergized.

The construction of the thread break detector 150 is shown more particularly in FIGS. 9, 10, and 11. As there shown, the detector is mounted upon the cover plate 79 for the head of the machine, there being a tubular metallic body 153 which projects through an opening in the cover plate and is affixed thereto. The forward end of body 153 is cut along a forwardly and downwardly inclined plane. Within the tube 153 there is disposed an electrical insulator 154 having a forward tubular skirt portion and a transverse solid portion 158 at the rear end thereof. The rear end of electrically conductive coil spring 155 is affixed to insulator 154 by being telescoped within a downwardly and forwardly inclined bore through the rear portion 158 of the insulator, electrical connection to the rear end of the spring being effected by a conductor 156 which is forcibly embraced by the rear end of the spring. Telescoped within the forward end of spring 155 and forcibly engaged therewith, with its rear end spaced somewhat from the forward end ofthe conductor 156, is the shank 157 of the electrically conductive pigtail guide 151, the lower surface of which acts as a first, upper contact of the two cooperating contacts of the thread break detector. The other, lower contact of the detector is here made in the form of a removable U-shaped clip 159 which is telescoped over the forward lower edge of the tubular body 153 and makes secure electrical contact therewith. The frame of the sewing machine is grounded, as shown in the circuit diagram in FIG. 15, to be described, so that when the pigtail guide 151 is in its lower position FIGS. 9 and 11) the conductor 156 is connected to ground.

As shown, when the thread 145 in the portion thereof passing through the guide 151 is slack or substantially untensioned, the guide 151 lies in its lowermost position and the contacts of the thread break detector are closed. When, however, such run of the thread 145 is tensioned, the thread pulls the guide 151 upwardly, thereby to flex the spring 155 and to separate the two contacts of the detector. As above mentioned, should the thread 145 of the sewing head be broken or depleted when it would otherwise normally be tensioned to separate such contacts as shown in FIG. 10, the contacts then engage each other whereby the signalling means 181 associated with such sewing head is energized and the entire machine is brought to a stop.

The manner in which such signalling device and the machine controlling circuit operates will be more fully understood upon consideration of FIGS. 2 and 15. As shown in the latter of such figures, the multiple head sewing machine is driven by a motor 164 having a motor shaft 165; shaft 165 is drivingly connected to the lower main driving shaft of the machine by the belt shown in FIGS. 1 and 7. The motor 164 is supplied with operating current from a source I.,, L through the normally open contacts of switches 200 and 201 of a relay C. It will be apparent that when the contacts of switches 200 and 201 are closed, the motor 164 will be connected to the current source to start the motor, the motor remaining running until such switches are opened.

To start motor 164 the coil 203 of relay C is energized by source L L through a temporarily manually closed starter switch 202, and the normally closed switch 172 of a relay B. The thus energized coil 203 closes switches 200 and 201, thus energizing the motor, and also closes a switch 204 in a holding circuit which connects'said coil across the source through switch 172 independently of starter switch 202. The switches of relay C will accordingly remain closed and the motor energized until coil 203 is deenergized by opening a stop switch 205 manually of opening switch 172 in a manner hereinafter described in response to the thread break or depletion detector 150.

As shown in FIG. 15, the control circuit for the machine includes a voltage stepdown transformer 167 having a primary winding 169 connected to the current source L L and a secondary winding 170 which is connected in and powers the control circuit. The control circuit is so constructed and arranged that upon the breaking or depletion of any one of the upper threads 145 being applied by the respective sewing heads of the machine the coil 174 of the relay Bis energized by the controlcircuit, whereby to open the contacts of switch 172 and to stop the motor 164.

A first terminal of the secondary winding 170 of the trans former 167 is connected to ground 206 through a normally closed reset switch 173 mechanically connected to starter switch 202, the one being open when the other is closed. The second terminal of the secondary winding is connected to a first terminal of the coil 174 of relay B. The other end of the relay coil 174 is connected to a first contact of a periodically opened and closed contact set 175. The other, second contact of such set is connected by a wire 184' to a terminal 194 ofa circuit portion 180. Between the second terminal of the secondary winding 170 and the relay coil 174 there is connected a wire 190 which leads to a terminal 195 of the circuit portion 180.

A first contact of a second periodically opened and closed contact set 177 is connected to wire 190, the other contact of such set being connected to a terminal 196 of the circuit portion 180. Although only one circuit portion 180 is shown in FIG. 15, there is actually a plurality of such circuit portions, one for each sewing head 10, the respective terminals 194, 195, and 196 of all said circuit portions being connected in series, so that, as above explained, the breaking of any one thread 145 not only energizes the respective signalling means 181 but also stops the entire machine. Since all of the circuit portions 180 are identical, only one need be described.

A wire 182, which is connected to terminal 196, leads to one fixed contact of a normally closed contact set 183 of a through a wire 184 to one terminal ofits respective signal light 181 which is mounted upon the front cover plate 79 of the respective sewing head. The other terminal of signal light 181 is connected by a wire 198 and a normally open switch 207 of relay A to terminal 194. The above described conductor 156 of the thread break detector 150 is connected to wire 198, as shown.

Also connected to wire 198 through a wire 189 is the first contact of a normally open third contact set 186 of relay A, the other contact of such set being connected directly to ground 208. A normally open fourth set of contacts 187 of relay A has one contact thereof connected to lead 184 and the other contact thereof connected through a wire 199 to terminal 195. The movable contactors of relay A are connected to move together, but are electrically insulated from each other. Such contactors are raised to close contact sets 186, 207, and 187 and to open contact set 183 when the coil 185 of relay A is energized. One terminal of coil 185 is connected to wire 184 and the other terminal thereof is connected to wire 198. Y

The cam operated contact sets 175 and 177 are shown more particularly in FIG. 2. Both of such contact sets are here constructed similarly to the low tension breaker points on an automobile, the movable contact of each set being constantly urged toward contact-closed position by a leaf spring, and being opened by a cam acting through a cam follower affixed to the movable contact. In the embodiment shown, the contact sets 175 and 177 are actuated by cams 176 and 179, which are affixed to shafts l6 and 15, respectively, as shown in FIG. 2. Since such contact sets are similar, only set 175 need be specifically described.

An electrically insulating contact supporting member 178 is secured to the outer face of support member 12. The fixed contact of the set is secured to member 178; the movable contact is mounted on one end of an electrically conducting lever arm which is pivotally mounted on member 178, the other end of the lever arm being connected through the pivot means to wire 184. Intermediate the length of the lever arm there is mounted a cam follower roll 183, which bears upon the rim of the outer flange ofsprocket 25, such rim forming the cam 176. The cam 176 is of circular shape coaxial of shaft 16 throughout its circumference with the exception of a cutout zone 192 wherein the leading end has an abrupt radially inwardly extending shoulder, the remainder of such zone constituting a ramp, the radius of which progressively increases until it reaches the radius of the remainder of the cam at the trailing end of such zone. The parts supporting and operating the contact set 175, including the cam 176 and cam follower 183, are so constructed and arranged that the contact set 175 remains open at all times with the exception of the period when the cam follower 183 rests upon the leading and intermediate portions of the cutout portion 192 of the cam 176. Similarly contact set 177 remains open at all times except during the period when the cam follower is in the cutout zone of cam 179. The sprocket 24 (and thus the cam 179) is affixed to shaft 15 in such angular position that the contact set 177 is closed during that period in the sewing cycle in which the upper thread is tensioned, as described in connection with FIG. 12, and is open at all other times. The contact set 175 and cam 176 are similarly positioned relative to shaft 16, except that cam 176 is angularly disposed to close contact set 175 a short interval after contact set 177 is closed by cam 179. Both cams are angularly adjustable relative to the driving shafts therefor.

The thread breakage detectors of the respective sewing heads and the control circuits of which they are parts function as follows. When an upper thread 145 ofa sewing head 10 is depleted or breaks, the upper contact 151 of the thread detector 150 of such head remains in engagement with the lower ground contact 159 thereof during that portion of the sewing cycle when such contacts would have been open if the thread were unbroken. As we have seen, the contact set 177 is closed during such portion of the cycle. When the contacts of the detector 150 are closed at the same time as the contacts of the contact set 177, the signal light 181 of the sewing head whose thread 145 has broken is energized by secondary winding 170 through wire 190, contact set 177, wire 182, contact set 183, and wire 184, and through wires 198 and 156, upper contact 151, the lower ground contact 159 of detector 150, ground return 206 and reset switch 173.

Simultaneously with the energization of the signal light 181, the coil 185 of relay A of the respective circuit portion 180 is energized by current flowing from winding 170 and wire 182 through such coil and to ground 159, 206 through wires 184, 198, and 156 and the contacts of the detector 150. Energization of such relay coil 185 causes the normally open contact sets or switches 186, 207, and 187 to close and contact set 183 to open. Closed switch 187 completes a holding circuit for relay coil 185 through wire 190, wire 199, switch 187, wire 184, coil 185, wires 198 and 156, and the contacts ofdetector 150 to ground 206. Such holding circuit bypasses the contact set 177, and thus the relay coil 185 remains energized after the opening of contact set 177 as shaft and cam 179 continue to rotate. An independent direct connection to ground for the signal light 181 and coils 185 and 174 of relays A and B, respectively, is simultaneously established through wire 198, wire 189, and the now closed switches 186 and 207. Such independent connection to ground, which is in parallel with the first mentioned connection to ground at 159 through the contacts of the detector 150, carries the greater part of the current required to energize the signal light 181 and the relay coils 185 and 174, and thus removes any possibility of unduly heating and weakening the current-carrying spring 155 of the thread break detector 150 should such signal light and relay coils remain energized for an extended period.

The described energization of the relay coil 185 of any one of the circuit portions 180 and the closing of its switches 186 and 207 also results in energization of the relay coil 174 when contact set 175 is subsequently closed. Thus upon the breakage of a thread 145 at any one of the sewing heads 10 of the machine, relay coil 174 is energized, when contact set 175 is closed, through a circuit from secondary winding 170 of transformer 167 to relay coil 174, contact set 175, wire 184', switch 207, and ground 206 by the above described alternate paths (1) through wire 189 and switch 186, and (2) through wire 156 and the contacts of the detector 150. The energization of relay coil 174 opens switch 172, thus breaking the holding circuit for relay coil 203 and thereby stopping the motor 164. Relay 8 remains energized only during the short period during which contacts 175 are closed. Motor 164 is preferably one of the type known as a "Unibrake" electric motor, which stops very quickly upon the opening of switches 200 and 201. The parts of the described machine may be so constructed and arranged that in the event of the breakage of a thread 145 of any of the sewing heads the machine will stop with all of the needle bars 81 of the heads in a raised position to allow rethreading. Timing in this respect may be varied by adjusting the cam 176 to vary the closing time of contacts 175.

Upon the stopping of the machine by the breakage of a thread 145, the lighted signal light 181 will immediately inform the operator which sewing head has the broken thread. The operator then rethreads such sewing head. During this time the relay coil 185 of the sewing head 10 being rethreaded will remain energized through the holding circuit and the signal light 181 of such head will remain energized. To start motor 164, the start switch 202 is momentarily manually closed, thereby momentarily opening reset switch 173. The circuit break at the latter opens the holding circuit for relay coil 185 and thus deenergizes it, so that switches 186, 207, and 187 are opened and switch 183 is closed, and the previously energized signal light 181 is deenergized. The control and signal circuit is now in its initial, operative or ready condition. The closing ofswitch 202 reenergizes relay coil 203 and starts the motor as described above.

Although only one embodiment of the invention has been illustrated in the accompanying drawings and described in the foregoing specification, it is to be especially understood that various changes, such as in the relative dimensions of the parts, materials used, and the like, as well as the suggested manner of use of the apparatus of the invention, may be made therein without departing from the spirit and scope of the invention as will now be apparent to those skilled in the art.

We claim:

1. A sewing machine having a sewing station, a sewing head having a housing supported above the sewing station, the sewing head having a reciprocable needle bar, a drive shaft for the sewing head, a drive train drivingly connecting the needle bar of the sewing head to said drive shaft, the drive train including a rotatable branch shaft extending transversely of the drive shaft and journaled in the housing and clutch means interposed between the branch shaft and the drive shaft, said clutch means comprising a first sleeve drivably connected to the drive shaft and axially fixed on the branch shaft for free rotation relative thereto and a second sleeve fixed against rotation on the branch shaft and movable axially thereon, means for selectively moving said second sleeve axially into and out ofdriving engagement with the first sleeve, and means connecting the needle bar to one end of said branch shaft independently of said clutch means.

2. A sewing machine as claimed in claim 1, wherein said clutch means is an indexing clutch, said sleeves of which have confronting formations thereon which mate in only one relative position thereof.

3. A sewing machine as claimed in claim 2, wherein said means for moving the second sleeve comprises an oscillatable clutch operating shaft journaled in the housing and extending outwardly from the clutch means, and eccentric means connected to the inner end of the clutch operating shaft for selectively engaging and disengaging the sleeves of the clutch means upon the turning of the clutch operating shaft in opposite directions.

4. A sewing machine as defined in claim 1 wherein a portion of the other end of the branch shaft projects from the housing for manual rotation whereby the needle bar may be manually actuated when the clutch means are disengaged.

5. A sewing machine as defined in claim 1 comprising a plurality of said sewing stations, a sewing head like said firstnamed sewing head and a housing therefor supported above each said station, and a drive train like said first-named drive train for connecting the needle bar of each sewing head to said drive shaft.

6. A multiple head embroidery machine having a plurality of aligned embroidering stations on a table, a plurality of aligned embroidering heads supported above the respective embroidering stations, each of the embroidering heads having a reciprocable needle bar, a common drive shaft for the embroidering heads extending along the aligned heads, a plurality of drive trains each drivingly connecting the needle bar of a respective head to said common drive shaft, and means for synchronously driving the ends of the common drive shaft.

7. A multiple head embroidery machine as claimed in claim 6, comprising a second, lower, common drive shaft extending beneath the table parallel to the first recited, upper common drive shaft, means for synchronously driving the ends of th common drive shaft, each of said heads having a rotatable loop former associated therewith, said loop formers being disposed in a row, and a drive train drivingly connecting the rotatable loop former associated with each head to said common lower drive shaft.

8. A multiple head embroidery machine as claimed in claim 7, wherein the heads and the loop formers associated therewith constitute sewing machines of the lock stitch type wherein first threads, inserted from above into the goods at the embroidery stations by needles carried by the needle bars of the heads, are locked with second threads supplied from beneath the goods, and comprising a bobbin disposed below the goods at each station, the loop formers being associated with the respective bobbins.

9. A multiple head embroidery machine as claimed in claim 7, wherein the means for driving the lower common drive shaft comprises means drivingly connecting corresponding ends of the common upper and the common lower drive shafts for rotation in synchronism.

10. A multiple head embroidery machine as defined in claim 7 comprising a variable speed driving coupling interposed in the lower common drive shaft adjacent each end thereof between the driving means for the corresponding end of such lower drive shaft and the drive train for the loop former at the corresponding end of the row thereof.

11. A multiple head embroidery machine as defined in claim 9 wherein corresponding ends of said common upper and common lower drive shafts are drivably connected by timing belts.

12. A multiple head embroidery machine as defined in claim 11 wherein both said timing belts are synchronously driven by a common power shaft.

13. A multiple head embroidery machine as defined in claim 12 comprising means for applying driving torque to said power shaft centrally thereof.

14. A sewing machine comprising a frame including a table for supporting goods to be sewed, a rail supported spaced above and generally parallel to the surface of the table, a sewing head having a housing supported on the rail, the machine presenting a clear path for goods beneath the sewing head and rail in a direction transverse to the rail, the sewing head having a reciprocable needle bar, a drive shaft for the sewing head extending above the table and generally parallel to the rail, a drive train drivingly connecting the needle bar of the sewing head to said drive shaft, said drive train comprising a branch shaft and clutch means mounted on said branch shaft, said clutch means comprising a first sleeve rotatable on and fixed against axial movement relative to said branch shaft and drivably connected to said drive shaft and a second sleeve axially movable on and fixed against rotation relative to said branch shaft for movement into and out of rotary driving engagement with said first sleeve, and driving means connected to the drive shaft for driving the drive shaft.

15. A sewing machine as claimed in claim 14 comprising a plurality of said sewing heads mounted in spaced relationship along the rail, the needle bar of each said sewing head being disengagably drivingly connected by a said drive train to the drive shaft.

16. A sewing machine as claimed in claim 15 wherein the driving means is drivably connected to both ends of the drive shaft for synchronously driving said ends of the drive shaft.

17. A sewing machine as claimed in claim 16 wherein each sewing head is adjustable along the rail and each said drive train comprises a gear rotatable with and adjustable longitudinally of the drive shaft for drivably engaging said first clutch sleeve of such drive train.

18. A sewing machine as claimed in claim 16 comprising a rotatable looper associated with the needle bar of each sewing head and disposed beneath the table, a drive train for each looper, and a second drive shaft for the loopers, the drive trains for the loopers and the second drive shaft being disposed beneath the table, the second drive shaft extending generally parallel to the first recited drive shaft, and means drivably connecting the ends of the second drive shaft to the ends of the first-named drive shaft for synchronous rotation therewith.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,595,188 Dated y 7, 97

Inventor) ALBERT A. SCHMEDDING and ERNEST L. PFEIFER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 12, line 59, before "common" insert lower Signed and sealed this 11th day of January 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GO'ITSCHALK Attesting Officer Acting Commissioner of Patents ORM PO-1050 [1 USCOMM-DC 60376-P69 LLS. GOVEINMENY PRINTING OFFICE 19.9 0-355-384 

1. A sewing machine having a sewing station, a sewing head having a housing supported above the sewing station, the sewing head having a reciprocable needle bAr, a drive shaft for the sewing head, a drive train drivingly connecting the needle bar of the sewing head to said drive shaft, the drive train including a rotatable branch shaft extending transversely of the drive shaft and journaled in the housing and clutch means interposed between the branch shaft and the drive shaft, said clutch means comprising a first sleeve drivably connected to the drive shaft and axially fixed on the branch shaft for free rotation relative thereto and a second sleeve fixed against rotation on the branch shaft and movable axially thereon, means for selectively moving said second sleeve axially into and out of driving engagement with the first sleeve, and means connecting the needle bar to one end of said branch shaft independently of said clutch means.
 2. A sewing machine as claimed in claim 1, wherein said clutch means is an indexing clutch, said sleeves of which have confronting formations thereon which mate in only one relative position thereof.
 3. A sewing machine as claimed in claim 2, wherein said means for moving the second sleeve comprises an oscillatable clutch operating shaft journaled in the housing and extending outwardly from the clutch means, and eccentric means connected to the inner end of the clutch operating shaft for selectively engaging and disengaging the sleeves of the clutch means upon the turning of the clutch operating shaft in opposite directions.
 4. A sewing machine as defined in claim 1 wherein a portion of the other end of the branch shaft projects from the housing for manual rotation whereby the needle bar may be manually actuated when the clutch means are disengaged.
 5. A sewing machine as defined in claim 1 comprising a plurality of said sewing stations, a sewing head like said first-named sewing head and a housing therefor supported above each said station, and a drive train like said first-named drive train for connecting the needle bar of each sewing head to said drive shaft.
 6. A multiple head embroidery machine having a plurality of aligned embroidering stations on a table, a plurality of aligned embroidering heads supported above the respective embroidering stations, each of the embroidering heads having a reciprocable needle bar, a common drive shaft for the embroidering heads extending along the aligned heads, a plurality of drive trains each drivingly connecting the needle bar of a respective head to said common drive shaft, and means for synchronously driving the ends of the common drive shaft.
 7. A multiple head embroidery machine as claimed in claim 6, comprising a second, lower, common drive shaft extending beneath the table parallel to the first recited, upper common drive shaft, means for synchronously driving the ends of the common drive shaft, each of said heads having a rotatable loop former associated therewith, said loop formers being disposed in a row, and a drive train drivingly connecting the rotatable loop former associated with each head to said common lower drive shaft.
 8. A multiple head embroidery machine as claimed in claim 7, wherein the heads and the loop formers associated therewith constitute sewing machines of the lock stitch type wherein first threads, inserted from above into the goods at the embroidery stations by needles carried by the needle bars of the heads, are locked with second threads supplied from beneath the goods, and comprising a bobbin disposed below the goods at each station, the loop formers being associated with the respective bobbins.
 9. A multiple head embroidery machine as claimed in claim 7, wherein the means for driving the lower common drive shaft comprises means drivingly connecting corresponding ends of the common upper and the common lower drive shafts for rotation in synchronism.
 10. A multiple head embroidery machine as defined in claim 7 comprising a variable speed driving coupling interposed in the lower common drive shaft adjacent each end thereof between the driving means for the corresponding end of such lower drivE shaft and the drive train for the loop former at the corresponding end of the row thereof.
 11. A multiple head embroidery machine as defined in claim 9 wherein corresponding ends of said common upper and common lower drive shafts are drivably connected by timing belts.
 12. A multiple head embroidery machine as defined in claim 11 wherein both said timing belts are synchronously driven by a common power shaft.
 13. A multiple head embroidery machine as defined in claim 12 comprising means for applying driving torque to said power shaft centrally thereof.
 14. A sewing machine comprising a frame including a table for supporting goods to be sewed, a rail supported spaced above and generally parallel to the surface of the table, a sewing head having a housing supported on the rail, the machine presenting a clear path for goods beneath the sewing head and rail in a direction transverse to the rail, the sewing head having a reciprocable needle bar, a drive shaft for the sewing head extending above the table and generally parallel to the rail, a drive train drivingly connecting the needle bar of the sewing head to said drive shaft, said drive train comprising a branch shaft and clutch means mounted on said branch shaft, said clutch means comprising a first sleeve rotatable on and fixed against axial movement relative to said branch shaft and drivably connected to said drive shaft and a second sleeve axially movable on and fixed against rotation relative to said branch shaft for movement into and out of rotary driving engagement with said first sleeve, and driving means connected to the drive shaft for driving the drive shaft.
 15. A sewing machine as claimed in claim 14 comprising a plurality of said sewing heads mounted in spaced relationship along the rail, the needle bar of each said sewing head being disengagably drivingly connected by a said drive train to the drive shaft.
 16. A sewing machine as claimed in claim 15 wherein the driving means is drivably connected to both ends of the drive shaft for synchronously driving said ends of the drive shaft.
 17. A sewing machine as claimed in claim 16 wherein each sewing head is adjustable along the rail and each said drive train comprises a gear rotatable with and adjustable longitudinally of the drive shaft for drivably engaging said first clutch sleeve of such drive train.
 18. A sewing machine as claimed in claim 16 comprising a rotatable looper associated with the needle bar of each sewing head and disposed beneath the table, a drive train for each looper, and a second drive shaft for the loopers, the drive trains for the loopers and the second drive shaft being disposed beneath the table, the second drive shaft extending generally parallel to the first recited drive shaft, and means drivably connecting the ends of the second drive shaft to the ends of the first-named drive shaft for synchronous rotation therewith. 